I've no idea about underground building in N.H. But in Florida it's a problem because of the very low water tables. Many places in Florida, a 20' hole would have 10' of water in it.

In the '70s underground utilities was all the rage here but they had lots of problems with groundwater affecting phone and power lines. Don't know what the outcome was. My service is all aerial except sewer and water of course.

Oops! My phone lines are buried.